Propagation of seismic exploration noise in the Marginal Ice Zone

Low-frequency information can reflect the basic trend of a formation, enhance the accuracy of velocity analysis and improve the imaging accuracy of deep structures in seismic exploration. However, the low-frequency information obtained by the conventional seismic acquisition method is seriously polluted by noise, which will be further lost in processing. Compressed sensing (CS) theory is used to exploit the sparsity of the reflection coefficient in the frequency domain to expand the low-frequency components reasonably, thus improving the data quality. However, the conventional CS method is greatly affected by noise, and the effective expansion of low-frequency information can only be realized in the case of a high signal-to-noise ratio (SNR). In this paper, well information is introduced into the objective function to constrain the inversion process of the estimated reflection coefficient, and then, the low-frequency component of the original data is expanded by extracting the low-frequency information of the reflection coefficient. It has been proved by model tests and actual data processing results that the objective function of estimating the reflection coefficient constrained by well logging data based on CS theory can improve the anti-noise interference ability of the inversion process and expand the low-frequency information well in the case of a low SNR.

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Helicopter-Based High-Resolution C/STD Observations in the Marginal Ice Zone--Field Analysis and Results on the Ocean Data Equipment Model 302

10.1109/oceans.1984.1152395 ◽

1984 ◽

Cited By ~ 2

Author(s):

T. Manley ◽

D. Perti

Keyword(s):

High Resolution ◽

Field Analysis ◽

Marginal Ice Zone ◽

Zone Field

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S-wave experiments for the exploration of a deep geothermal carbonate reservoir in the German Molasse Basin

Geothermal Energy ◽

10.1186/s40517-021-00189-w ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Britta Wawerzinek ◽

Hermann Buness ◽

Hartwig von Hartmann ◽

David C. Tanner

Keyword(s):

Upper Jurassic ◽

Carbonate Reservoir ◽

P Wave ◽

Seismic Survey ◽

Seismic Exploration ◽

Molasse Basin ◽

S Wave ◽

Induced Earthquakes ◽

Conversion Point ◽

Facies Classification

AbstractThere are many successful geothermal projects that exploit the Upper Jurassic aquifer at 2–3 km depth in the German Molasse Basin. However, up to now, only P-wave seismic exploration has been carried out. In an experiment in the Greater Munich area, we recorded S-waves that were generated by the conventional P-wave seismic survey, using 3C receivers. From this, we built a 3D volume of P- to S-converted (PS) waves using the asymptotic conversion point approach. By combining the P-volume and the resulting PS-seismic volume, we were able to derive the spatial distribution of the vp/vs ratio of both the Molasse overburden and the Upper Jurassic reservoir. We found that the vp/vs ratios for the Molasse units range from 2.0 to 2.3 with a median of 2.15, which is much higher than previously assumed. This raises the depth of hypocenters of induced earthquakes in surrounding geothermal wells. The vp/vs ratios found in the Upper Jurassic vary laterally between 1.5 and 2.2. Since no boreholes are available for verification, we test our results against an independently derived facies classification of the conventional 3D seismic volume and found it correlates well. Furthermore, we see that low vp/vs ratios correlate with high vp and vs velocities. We interpret the latter as dolomitized rocks, which are connected with enhanced permeability in the reservoir. We conclude that 3C registration of conventional P-wave surveys is worthwhile.

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